Piston for internal combustion engine

Abstract

Provided is a piston for an internal combustion engine. The piston includes a body including, at an upper part of the body, a crown including a combustion chamber where fuel is burnt and including, at a lower part of the body, a piston pin boss into which a piston pin is inserted and a skirt corresponding to a cylinder wall, and a cooling channel including a refrigerant channel, a refrigerant inlet provided at a side of the refrigerant channel, and a refrigerant outlet provided at the other side of the refrigerant channel, wherein a cross section of the cooling channel has an overall elliptic shape to reduce stress occurring at an upper side of the cooling channel when the fuel is burnt in the internal combustion engine, and at least one of arcs of the ellipse is configured as a first elliptical arc of a quadratic curve.

What is claimed is: 
     
       1. A piston for an internal combustion engine, the piston comprising:
 a body comprising, at an upper part of the body, a crown comprising a combustion chamber where fuel is burnt and comprising, at a lower part of the body, a piston pin boss into which a piston pin is inserted and a skirt corresponding to a cylinder wall; 
 a cooling channel comprising a refrigerant channel provided in the body to allow a refrigerant to flow therethrough to cool the body, a refrigerant inlet provided at a side of the refrigerant channel, and a refrigerant outlet provided at the other side of the refrigerant channel; and 
 a reinforced part having a shape of a fourth elliptical arc of a quadratic curve and provided at a lower surface of the crown and a part where the piston pin boss is connected to the skirt, 
 wherein a cross section of the cooling channel has an overall elliptic shape to reduce stress occurring at an upper side of the cooling channel when the fuel is burnt in the internal combustion engine, and at least one of arcs of the ellipse is configured as a first elliptical arc of a quadratic curve, and 
 wherein a ratio of a fourth minor axis to the fourth major axis of the fourth elliptical arc is 55% to 60%. 
 
     
     
       2. The piston of  claim 1 , wherein a first major axis corresponding to a line segment on an axis connecting two focal points of the first elliptical arc is provided in a length direction of the ellipse, and a first minor axis corresponding to a line segment perpendicular to the axis connecting the two focal points is provided in a width direction of the ellipse. 
     
     
       3. The piston of  claim 2 , wherein a ratio of the first minor axis to the first major axis of the first elliptical arc is 60% to 65%. 
     
     
       4. The piston of  claim 2 , wherein a ratio of the first minor axis to a width of the ellipse is 55% to 60%. 
     
     
       5. The piston of  claim 2 , wherein, in the cooling channel, at least one of the arcs of the ellipse is configured as a second elliptical arc of a quadratic curve, the second elliptical arc having a second major axis different from the first major axis and a second minor axis different from the first minor axis. 
     
     
       6. The piston of  claim 1 , wherein the upper side of the cooling channel is provided higher than a top ring groove located at a highest position among ring grooves in an outer circumferential surface of the crown. 
     
     
       7. The piston of  claim 1 , wherein a distance from the upper surface of the crown to the upper side of the cooling channel is 7 mm to 9 mm. 
     
     
       8. The piston of  claim 1 , further comprising an oil groove recessed in a height direction of the body near the refrigerant inlet or the refrigerant outlet at a part where the piston pin boss is connected to the skirt. 
     
     
       9. The piston of  claim 8 , wherein at least one of a lower inner circumferential corner and a lower outer circumferential corner of the oil groove is configured as a third elliptical arc of a quadratic curve to reduce stress occurring near the refrigerant inlet and the refrigerant outlet when the fuel is burnt in the internal combustion engine. 
     
     
       10. The piston of  claim 9 , wherein a ratio of a third minor axis to a third major axis of the third elliptical arc is 75% to 85%.